溫室氣體排放調查與減量研究-以某TFT-LCD廠為例

Abstract

近年來，平面顯示器產業為政府擬定「兩兆雙星核心優勢產業」發展的重點，TFT-LCD由於具有低輻射省能源的特點，已漸漸的取代傳統 CRT，目前全球使用情形相當普遍。但其在製造過程對環境所帶來的衝擊在所難免。本研究以TFT-LCD廠為例，研究TFT-LCD在製造過程中可能產生的溫室氣體，並建立可行之本土化溫室氣體盤查程序，首先設定實廠的組織邊界、營運邊界，接下來進行可能產生之溫室氣體排放源、活動強度調查及排放係數選定，最後進行排放量計算及統計。 研究結果顯示，TFT-LCD製造過程產生之溫室氣體主要為CO2、NF3及SF6，其中CO2之排放主要來自範疇2向台電購電所造成之間接排放，約佔總溫室氣體排放量之54%，而NF3及SF6之排放主要來自範疇1之薄膜(Thin film)及乾蝕刻(Dry Etch)製程之直接排放，約佔總溫室氣體排放量之44%，此兩類排放源之排放量合計約佔總排放量之90%以上。 為了進一步了解範疇1之排放減量機會，實場進行薄膜及乾蝕刻製程之燃燒式尾氣處理設備之處理效率檢測值(ηi)，結果顯示，其處理效率均可達99%以上，對PFCs減量具有實質效益。分別以檢測之處理效率ηi值及IPCC公告之處理效率ηi值，以Tier 2C計算排放量發現以IPCC公告值計算有高估排放量之情形。在相同條件下進行不同世代廠之PFCs排放量分析，比較結果發現世代越大，它在單位投片面積之PFCs排放量有下降的趨勢。在減量成本分析上，以燃燒式尾氣處理設備處理1噸之CO2 碳當量，平均每噸之處理成本為新台幣133.7元。但各世代處理1噸之CO2 碳當量之成本分析仍有待後續研究及探討。

In recent years, the flat panel display industry is the most important industry for the government. Due to the low radiation and energy conservation characteristics of TFT-LCD, it took place of CRT gradually. It is now widely used worldwide. This study investigates a TFT-LCD panel company to find out all the possible greenhouse gas emissions that are generated in the TFT-LCD manufacturing process and to buildup a feasible localized greenhouse inventory investigation procedures. The procedures start with setting the organizational and operational boundaries, then identifying greenhouse gas emission sources and activities strength and electing emission factors, and finally proceeding to emission quantity calculation and statistic analysis. The study shows the main greenhouse gas emissions from TFT-LCD manufacture process is CO2, NF3 and SF6, where the emission of CO2 is resulted from the scope2–indirect emissions, purchasing electricity from Taipower company, which makes up 54% of total emission. While the emission of NF3 and SF6 are mainly from the scope 1 – direct emissions of CVD and Dry Etch process, accounting for 44% of total emissions. The two types of emission sources account for over 90% of total emissions. To further understand the possibility of reducing scope 1 emission, on-site measurement of the abatement efficiency of burning type local scrubbers for CVD and Dry Etch processes were conducted. The results showed the removal efficiency,ηi values were all greater than 99%, which was effective in reducing PFCs. When calculating with Tier 2C to get the amount of emission by using the measured removal efficiency and IPCC published default values independently, the result based on IPCC published default values shows over estimation. By analyzing the PFCs emission of plants of different generation under the same condition, it is found that the larger the generation is, the lower the PFCs normalized emissions (ton/m2 of substrate). In PFCs reduction cost analysis, the cost of PFCs reduction with burning type local scrubber is about 133.7 NTD / ton CO2 equivalent. However, the estimation of the PFCs reduction cost for plants of different generation still need further study.